Gaithersburg's Accessory Structures: The Rules That Matter

Every city handles accessory structures a little differently. In Gaithersburg, Maryland, there are 5 distinct rules that residents and property owners should be aware of. Some are stricter than what neighboring cities enforce, and others are more relaxed. Here is what you need to know.

Tiny Homes

Tiny homes in Gaithersburg must comply with the International Residential Code minimum standards for dwelling units. Tiny homes on foundations may qualify as accessory dwelling units subject to ADU regulations. Tiny homes on wheels are classified as recreational vehicles and cannot be used as permanent residences. Minimum dwelling unit size is generally 150 square feet under the IRC Appendix Q provisions.

Key details: On Foundation: Permitted as dwelling or ADU. On Wheels: Not allowed as permanent residence. Minimum Size: ~150 sq ft under IRC Appendix Q. ADU Rules Apply: Yes, for accessory units. Building Division: (301) 258-6330.

Occupying a tiny home on wheels as a permanent residence violates the zoning ordinance and may result in cease-occupancy orders. Tiny homes that do not meet IRC minimum standards for habitable space cannot receive a certificate of occupancy. Unpermitted construction faces standard code enforcement penalties.

Garage Conversions

Converting a garage to living space in Gaithersburg requires a building permit and zoning review. The conversion must meet residential building code standards for habitable space including egress, insulation, ventilation, and ceiling height. Off-street parking requirements must still be satisfied after the conversion. Garage-to-ADU conversions follow the city's accessory dwelling unit regulations.

Key details: Permit Required: Yes — building permit. Ceiling Height: 7 feet minimum. Parking Impact: Must maintain minimum spaces. ADU Option: Subject to ADU regulations. Building Division: (301) 258-6330.

Converting a garage without permits is a building code violation. Habitable space that fails to meet egress, ventilation, or ceiling height standards is a life-safety violation subject to immediate correction orders. Loss of required parking spaces without zoning approval is a separate violation.

Shed Rules

Storage sheds in Gaithersburg are regulated by the city's zoning ordinance and building code. Sheds under 200 square feet do not require a building permit but must comply with setback and height requirements. Sheds 200 square feet or larger require a building permit. All sheds must be in rear yards and set back at least 3 feet from property lines in most residential zones.

Key details: Permit Threshold: 200 sq ft and larger. Max Height: 15 feet. Setback: 3 feet from property lines. Location: Rear yard only. Building Division: (301) 258-6330.

Building a shed over 200 square feet without a permit is a code violation. Sheds placed in required setbacks or front yards face removal orders. Exceeding lot coverage limits triggers enforcement action. Using a shed as a dwelling is a zoning violation subject to immediate cease-and-desist orders.

Carport Rules

Carports in Gaithersburg are treated as accessory structures and require a building permit. They must meet setback requirements for the applicable zoning district. Carports may be attached or detached from the primary dwelling. Front-yard carports are generally not permitted in single-family residential zones unless approved through the site plan process.

Key details: Permit Required: Yes. Setback: 3 feet from property lines (detached). Max Height: 15 feet. Front Yard: Generally not permitted. Building Division: (301) 258-6330.

Building a carport without a permit is a code violation subject to stop-work orders and potential removal. Carports encroaching into required setbacks require a variance or must be relocated. Exceeding lot coverage limits triggers enforcement action.

ADU Rules

Gaithersburg permits accessory dwelling units in most residential zones following its ADU-friendly zoning amendments. ADUs may be attached to or detached from the primary dwelling. Units are limited to 50 percent of the primary dwelling floor area or 1,200 square feet, whichever is less. One off-street parking space is required. Owner occupancy of either the primary or accessory unit is required.

Key details: ADU Allowed: Yes, in most residential zones. Max Size: 50% of primary or 1,200 sq ft. Owner Occupancy: Required in primary or ADU. Parking: 1 space (waiver near transit). Planning Dept: (301) 258-6330.

Operating an ADU without zoning approval and building permits is a code violation. Unpermitted units face correction orders, potential fines, and orders to cease occupancy. Owner-occupancy violations may result in revocation of the ADU approval. Building code deficiencies must be corrected before occupancy is permitted.

The rules around adu rules in Gaithersburg lean permissive, but that does not mean anything goes.

The Bottom Line

Gaithersburg's accessory structures rules are a mixed bag. Some areas are strict, others are relaxed, and the details matter. The best approach is to check the specific rule that applies to your situation rather than assuming Gaithersburg is broadly strict or permissive.

This guide is based on Gaithersburg's current municipal code. Local rules can and do change, so check the individual ordinance pages for the latest details, penalties, and FAQs.